Recently, Associate Professor He Wei from King's College London, UK, and his collaborators have developed a new type of highly flexible electrodialysis technology, which has improved the application efficiency of solar desalination technology and mitigated the impact of the intermittent nature of solar power on the technical performance and economic viability.

As a new type of "energy storage" desalination technology, the electrodialysis technology developed in this study can, like energy storage technology, efficiently convert intermittent solar energy and store it in purified drinking water.

Through this, it is possible to decouple the energy supply from the energy consumption of drinking water production, meeting the water resource needs of residents in specific areas.

It can also provide a sustainable drinking water solution for remote rural areas that lack a stable power grid supply.

At the same time, compared with traditional freshwater desalination technologies that rely on grid power or rely on expensive battery energy storage systems, this study aims to directly convert solar energy into drinking water through "energy storage" desalination technology, thus getting rid of the dependence on battery energy storage.Considering that the cost of water storage is far lower than the cost of battery energy storage, this technology not only improves the efficiency of energy utilization but also enhances the economic viability of solar desalination technology.

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Recently, the relevant paper was published in Nature Water with the title "Flexible batch electrodialysis for low-cost solar-powered brackish water desalination" [1].

He Wei is the first author and co-corresponding author, and Professor Amos G. Winter V from the Massachusetts Institute of Technology in the United States serves as the co-corresponding author.

Specifically, this electrodialysis technology is expected to be used in the following scenarios:

Firstly, it can be used for the supply of drinking water in remote areas.

As mentioned earlier, since this technology can directly convert solar energy into desalinated water, it is particularly suitable for remote areas with unstable power grids or where the power grid has not yet been covered.At that time, residents in these areas will be able to directly obtain safe drinking water from underground brackish water sources, thereby improving the supply of drinking water.

Secondly, it is used for agricultural irrigation.

In agricultural areas with tight water resources, this technology can be used to provide the fresh water needed for irrigation.

Especially in areas with more saline-alkali soil, using the electrodialysis technology to desalinate water can effectively reduce soil salinity, thereby increasing the yield and quality of crops.

Thirdly, it is used for the recovery of industrial high-salt wastewater.Many industrial processes, such as food processing, generate a large amount of saline wastewater. In the recovery and treatment of saline wastewater, electrodialysis technology can significantly improve its efficiency.

Fourthly, it is used for lithium extraction from salt lakes.

Electrodialysis technology can efficiently extract lithium ions from salt lakes and can integrate the lithium extraction process with new energy sources such as solar energy, thereby converting solar energy (including abandoned light) into high-value lithium materials, and then extracting lithium ions in a low-emission, high-quality manner.

Approximately 1.7 billion people live in areas with water scarcity.According to the report, this study is based on the severe background of global water scarcity, with a particular focus on the challenges of drinking water shortages faced by rural areas in developing countries.

Currently, over 2 billion people worldwide rely on groundwater as a source of drinking water, but about 1.7 billion people live in areas where water resources are scarce.

Due to salinization caused by natural and human factors, the quality of groundwater is gradually deteriorating, making many water sources salty or saline, and not suitable for direct drinking.

Although traditional seawater/saline water desalination technology can effectively extract fresh water, its widespread dependence on the power grid and infrastructure limits its application in remote areas.

Especially in many developing countries, such as remote areas of India, there is either no power grid coverage or the power grid is subject to power outages. In addition, most of the electricity comes from coal-fired power plants, leading to high carbon emissions.However, these areas are typically abundant in sunlight, so distributed solar-powered desalination technology can serve as a sustainable and universal solution to address the water scarcity problem in remote areas.

It is reported that this study originated from a project by He Wei's collaborator, Amos G. Winter V from the Massachusetts Institute of Technology in the United States.

Previously, the latter had cooperated with India's Tata company to carry out a series of research projects aimed at addressing the shortage of water resources for drinking and agricultural irrigation.

Later, Professor Tonio Buonassisi from the Massachusetts Institute of Technology also joined the aforementioned project.

Through this, a technical route using solar energy for underground desalination of saline water and agricultural drip irrigation was established, with the hope of expanding water resource utilization and reducing water consumption.At the same time, the economic advantages of using photovoltaic-electrodialysis technology for solar desalination of saline water were also clarified. It was at this moment that He Wei joined the aforementioned project.

To further reduce the cost of photovoltaic-electrodialysis technology, they established the design theory of photovoltaic-electrodialysis technology using first principles, and optimized the design of the photovoltaic-electrodialysis technology system based on this theory.

In 2017, the first prototype system was completed and tested in a village in India called Chelluru.

Through this, they not only verified the theory of the photovoltaic-electrodialysis technology model and system design, but also gained a deep understanding of the specifications and cost considerations of desalination systems in rural areas of India.

They found that although the cost of photovoltaic-electrodialysis technology is lower than that of solar reverse osmosis (PV-RO, Photovoltaic-Reverse Osmosis) systems. However, compared with grid-driven reverse osmosis (on-grid RO, on-grid Reverse Osmosis) systems, the cost advantage is not prominent enough.While on-grid reverse osmosis (RO) systems have been commercialized in rural areas of India, this indicates that photovoltaic-electrodialysis technology has not yet reached a market-acceptable cost, or it is still unable to form a business model for desalination systems for brackish water locally.

Although the cost of the first prototype system has not yet reached the level of commercialization, this on-site test in India not only confirmed their design theory but also provided valuable on-site information.

Based on this information, the research team further innovated the electrodialysis technology, proposing a more flexible electrodialysis technology that can flexibly adjust the water production according to the changes in solar energy supply.

Subsequently, they built a new prototype system at the Brackish Groundwater National Desalination Research Facility in India.

And using the relevant test platform, they carried out more accurate monitoring and evaluation of this technology.The test results indicate that the system's energy efficiency has been significantly improved, with 77% of the available solar energy being directly utilized. This is 91% higher than traditional systems, while battery dependency has been reduced by 92%.

When analyzing these field test results, combined with the team's understanding of the desalination project for Indian villages, they found that the cost of water was reduced by 22%, allowing this technology to be comparable to the widely used on-grid RO systems.

During the field visit to India, while testing the first prototype system, something happened that made He Wei feel very "counterintuitive."

During the test, the entire system was powered by solar photovoltaic panels. However, the lights at the experimental site were connected to the power grid and would only automatically switch to the solar system during a power outage, emitting a "beep" sound when switching.

This allowed them to more frequently experience power outages from the grid. Especially at night, they were often the only ones with the lights on."The intermittency of new energy, which was once criticized, has instead become a reliable source of power here, while the power grid, which should have provided stable power in many countries, has become a truly intermittent energy source," he said.

This experience has enhanced his and his collaborators' understanding of new energy, that is, although the sun is a distributed energy source, it can significantly enhance the stability of energy supply in remote areas.

In the next step, they plan to expand the application of flexible electrodialysis technology beyond desalination of brackish water.

Considering the versatility and high efficiency of electrodialysis technology itself, its potential applications in different fields will undoubtedly have a significant positive impact, such as applications in agricultural irrigation, lithium extraction from salt lakes, and capturing carbon dioxide using liquid alkali, etc.

The new energy industry chain is mainly concentrated in China, looking forward to cooperating with domestic units.It is also reported that as a native of Xi'an, although he did not live in a coastal city, He Wei began to learn about seawater/saline water desalination technology during his studies in Xi'an.

He graduated from Xi'an Jiaotong University with both his bachelor's and master's degrees, and later obtained a doctorate from Queen Mary University of London.

He said: "Although I felt a bit confused when filling in my college entrance examination preferences, I may have been influenced by environmental reports since I was a child, and a vision for the future has already taken root in my heart: new energy will become a key technology for the future."

Under the guidance of this belief, he chose the Energy and Power Engineering major at Xi'an Jiaotong University.

During his postgraduate studies, he participated in a water treatment research project funded by a company, where he first came into contact with seawater and saline water desalination technology, and began to explore how to more efficiently obtain fresh water from brine from an energy perspective.After coming to the UK to pursue his PhD, he further studied the integration mechanisms and applications of seawater desalination technology with various new energy sources.

During his postdoctoral period at the Massachusetts Institute of Technology in the United States, he shifted his research focus to solar electrodialysis technology.

"It is my research in this field that has earned me the Research Fellowship support from the Royal Academy of Engineering in the UK, starting my career as an independent Principal Investigator," he said.

Energy technology, as a key hard technology, covers a large amount of research and development of hardware and software against the backdrop of the era of intelligence and digitalization.

Especially in the process of industrialization of technology, hardware development inevitably needs to rely on the support of the industry chain and supply chain.Currently, the new energy industry chain is mainly concentrated in China. He is deeply interested in exploring and establishing opportunities for the transformation of the new energy industry, including new electrodialysis technology. "He also looks forward to cooperation with domestic universities and enterprises," he said.